In general, an anti-reflective film is disposed on the flat panel display devices such as PDP, LCD or the like in order to minimize the reflection of external light.
The commonly used anti-reflective film has a three-layer structure of a hard coat layer and high and low refractive index layers with a thickness of 1 μm or less, which are laminated on a light-transparent substrate film. A two-layer structure of high and low refractive index layers laminated on the substrate film has been also commercialized in order to simplify the production process.
These anti-reflective films are manufactured by a dry or wet method.
Of the methods, the dry method is a method of laminating a low refractive index material (e.g., MgF2, SiO2, etc.) as a thin film or alternately laminating a high refractive index material (e.g., ITO (tin-doped indium oxide), ATO (tin-doped antimony oxide), ZnO, TiO2, etc.) and the low refractive index material on the substrate film by deposition or sputtering. The drying method has an advantage of manufacturing anti-reflective films having superior adhesion at a film interface, but requires high production cost, which is a limitation for commercial use.
Meanwhile, the wet method is a method of drying and curing a coating composition containing a polymer resin, an organic solvent, etc., after applying it onto the substrate film. This method is less expensive than the dry method, and thus widely used in commercial applications.
In the wet method, however, processes for forming the hard coat layer and the high and low refractive index layers included in the anti-reflective film should be conducted separately. Thus, the production process becomes complicated, and offers weak adhesion at a film interface.
For this reason, many studies have been actively made to develop an anti-reflective coating composition capable of forming two or more layers by a single wet coating process.
However, there are still many problems that phase separation does not properly occur upon applying the composition during the production process, and thus individual layers deteriorate in functions, or scratch resistance of the low refractive index layer placed on the film surface deteriorates.